Self-tensioning link assembly



Feb. 1963 D. M. NELSON SELF-TENSIONING LINK ASSEMBLY 2 Sheets-Sheet 1 Filed Oct. 19, 1959 INVENTOR. DONALD M. NELSON ATTORNEY Feb. 12., 1963 D. M. NELSON 3,077,328

SELF-TENSIONING LINK ASSEMBLY Filed Oct. 19', 1959 2 Sheets-Sheet 2 FIG. 2

INVENTOR. DONALD M. NELSON BY flo 5 2 M ATTORNEY 3,677,328 Patented Feb. 12, 1963 3,077,328 SELF-TENSHGNENG LENK ASEMELY Donald M. Nelson, Compton, fialitl, assignor to North American Aviation, inc.

Filed st. 19, 1959, Ser. No. 847,334 10 Qiaims. ((131. 248-617) This invention relates to a novel self-tensioning link assembly, and more particularly to a self-tensioning link assembly having novel preloading spring means adapted to support a suspended member with a predetermined tension. The link assembly particularly finds indispensable utility when used with an astro-tracker in the pylon of a missile whichis supported by an autonavigator prior to the launching of a missile. Novel control means are mounted on the side of the link assembly and are so positioned so as to be easily accessible for the control and maintenance thereof.

The prior art suggests many preloading mechanisms which are bulky and expensive as well as being so COD: structed that the operation thereof is diflicult, if not impossible. The problem of maintaining a predetermined tension on a member to be suspended is of the utmost importance, especially in the supporting of an astro-v tracker, since forces imparted thereto by the missile vibra-. tions are apt to damage the very delicate instrumentations therein.

This invention overcomes the inadequacies of the prior art by providing a novel self-tensioning link assembly having readily accessible control means utilized to impart tension to a spring means and then by subsequently clamping the attached member in a positive position maintaining a predetermined tension on the suspended member.

An object of this invention is to provide a self-tensioning link assembly which may be easily applied to a suspended member so as to impart a predetermined tension thereto and simultaneously lock the suspended member to the link assembly, thus maintaining the predetermined tension therein.

Another object of this invention is to provide novel control screw cam means mounted on the side of the link assembly which control is easily accessible for preloading purposes.

Although the prime objects of this invention have been set forth, when the following specification and claims are read in connection with the drawings, other objects and features of the invention will become apparent.

. FIG. 1 is a side view of the self-tensioning link assembly in disconnected or open position.

FIG. 2 shows the self-tensioning link assembly of FIG. 1 as applied to a suspended member with the link as: sembly and suspended member subjected to a predetermined tension.

FIG. 3 is a right hand side View of the self-tensioning link assembly of FIG. 2.

FIG. 4 is a top view of FIG. 2.

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 2.

FIG. 6 is a cross-sectional view taken on line 66 of FIG. 2.

The invention comprises a tension link assembly com-. prising a plate member which is adapted to be fastened to a support structure. A pivot pinpivotally mounts a housing which slidably contains the fastening member. The lower end of the fastening member is constructed in ahook-like fashion and is adapted to be secured to complementary fastening means on the member to be sup ported. Compression spring means encircle the fastening member and is adapted to be compressed by bell crank control means pivotally mounted on the side of the housing. Screw cam means project from the side of the housing and have a cam portion thereon adapted to cooperate with a cam seat formed on the bell crank control means. When the tension imparted to the member to be supported is approached, further turning of the screw cam means secures the fastening member in a vise-like manner by means of a compression surface formed on the bell crank control means co-acting with a compression surface formed on the housing.

The preferred embodiment of this invention, as shown in FIG. 1, discloses the self-tensioning link assembly as it would appear prior to its connection with an attached member 1 to which it is desired to impart a predetermined supporting tension.

The member 1, to be suspended from the upper structure, has an upstanding post 2 fixedly secured thereto by bolts 3. On the upper extremity of the post 2, an eye member 4 is inserted in bushings 5 fixed to the post. A shear pin 6 projects through the bushings and eye member to form an attachment therebetween. The bushings are fixedly retained in post 2. by means of a washer 5a. In the specific illustrated embodiment the shear pin is so constructed that the eye member 4 will detach from the post 2 and bushing 5 upon a predetermined longitudinal separation force thercbetween.

The above described attached member discloses one specific assembly, but it is to be understood that the attached member may take any desired form depending on the operational requirements.

A supporting member A from which it is desired to suspend member 1 has the link assembly including a sta-. tionary plate 7 mounted thereon by bolts 8. A pivot pin 9, shown as extending across a hole in plate 7 (FIG. 4), pivotally mounts a housing 10. At the lower end of the housing 10 an internally threaded portion 11 projects on the side thereof. A threaded end 12 of a setscrew 13 00-. operates with threaded portion 11 of housing 10 to c0n-v trol the longitudinal movement of setscrew 13. A trans: rse e n in P n 1 m ts e h war ent setscrew 13 by abutting the surface 19;: of cylindrical hou n 0. a Shown i FIG- l.- A omp s n ne curing surface 1% of housing 10 is adapted to abut a complementary clamping surface 211:; of hook member 21.

A cam portion 15 on screw 13 cooperates with cam seat 15 on a bell crank 17 to pivot said bell crank. The face of the bell crank is formed with a compression surface 17a, the function of which will be later described. A pivot pin 1-8 mounts the bell crank on the housing 10. The beli crank is extended to form a cam comprising fork members 19 and a seat 243. A fastening hook member 21 hava ing clamping surface 21b formed thereon, is contained in the housing 10 and has a first washer 22. slidably mounted on the mid-portion and a fixed washer 23 mounted on the top thereof. A compression spring 24 is mounted between the washers.

A shoulder 25 is formed on the hook member and the flange 24) of the bell crank 17 is adapted to lie between this shoulder and the slidable washer 22 when the assembly is in disconnected position. A transverse hole 26 is formed in the hook member so as to provide a passage with sufficient clearance whereby the setscrew may be inserted. The clearance further assures that the hook member 21 has complete freedom upon the longitudinai movements thereof within housing 10.

The lower extremity of the hook member is formed with the hook portion 27, which is adapted to cooperate with the eye member 4 to form an attachment therebetween as shown in FIG. 2. A projectio n 23 limits the clockwise swinging movement of the tension link assembly being adapted to abut post 2 as in FIG. 2.

A tension spring 29 is attached at one end to the sta-, tionary plate '7 and at the other end to the bell crank 17 so as to bias the tension link assembly in a counterclockwise direction into the inoperative position of FIG. -1.

- From the aforedescribed novel arrangement, it is apparent that the tension link assembly may be positioned in very confining areas while providing simple control means which are readily accessible for preloading.

Operation When it is desired to support an attached member with a predetermined tension the tension link assembly of FIG. 1 is pivoted in a clockwise direction so that the hook 27 is inserted in the eye member 4. A conventional torque wrench is placed on the setscrew 13 and the screw is rotated. until the predetermined torque is achieved. Any type of conventional cooperating torque imparting tool may be utilized to rotate setscrew 13, depending on the available tools and operational requirements.

As clearly shown in FIG. 2, upon the turning of the setscrew 13, the bell crank 17 is pivoted in a clockwise direction, consequently raising washer 22. The washer 22 in turn imparts a compression force to spring 24 which force is directly transmitted to the fastening hook member 21 by Way of the fixed washer 23. The hook 27 is consequently biased in an upward direction thus, imparting a lifting force to eye member 4 and attached member 1.

Simultaneously with achieving the predetermined tension as noted on a conventional torque indicating wrench, for example, the device as shown is so constructed that upon turning of the setscrew 13 the compression surface 17a of bell crank 17 cooperates with the opposing compression surface ltlb of housing to grip hook member 21 in a vise like manner due to the arrangement of clamping surfaces 21a and 21b thereon. Consequently, the fastening hook member 21 and suspended member 1 are secured and supported at a predetermined tension.

The tension link assembly may be utilized to function as a shock absorber, that is, to allow the assembly to absorb sudden extreme shocks by adjusting the setscrew so that the friction as between surfaces 17a-21b and 10b and 21a respectively will compensate for an extreme load imparted to the suspended member 1. However, it is obvious that the embodiment as shown will permit the further-step of locking the attached member 1 at a predeterminedtension.

- The aforedescribed self-tensioning link assembly finds considerable utility in the missile industry wherein an astro-tracker in a pylon must'be suspended from a stabilized platform of the autonavigator under a predetermined tension. In this specific application, suspended member 1 constitutes the astro-tracker which is mounted and carried on a missile during its flight pattern. Upon releasing the missile, pin 6 is sheared and the astro-tracker is free to fall with the missile. The maximum load which the pin 6 is capable of carrying prior to the shearing thereof is, of course, determined before the installation thereof.

In such an application, it is desirable to put some tension on the astro-tracker, however; not to a degree which would prematurely shear pin 6. At the same time the astro-tracker must be supported on the autonavigator with suificient tension to hold the astro-tracker in a relative firm and stable position prior to the missile launching.

Previous astro-tracker support assemblies provided a relatively large shear pin 6, which pin when sheared upon the missile release would cause a severe jolt to the autonavigator causing the failure thereof.

It is to be again noted that such a novel self-tensioning link assembly is adapted to be placed in very confining areas and is readily accessible to the operator for expeditious control thereof.

Although one specific embodiment of the invention has been illustrated it is obvious that various changes and modifications may be made thereto without departing from the scope of the invention.

Iclaim: 1. A tension link assembly comprising: pivot means on a member pivotally mounting a housing; a fastening member slidably mounted in said housing and having a hook means on the lower end thereof adapted to tensionally support a suspended member; compression means for urging said fastening member in an upward direction; bell crank means mounted on said housing for urging said compression means into a compressed condition; means mounting said bell crank for limited motion to limit the compressive force exerted by the bell crank upon said compression means to a predetermined amount; means mounted to the housing and engaged with the bell crank for imparting said limited motion to said bell crank means so as to impart a predetermined support tension to the suspend-ed member.

2. The tension link assembly of claim 1 further comprising: a projection on said fastening member adjacent said hook means adapted to engage the suspended member so as to limit the pivotal movement of said fastening member.

3. The tension link assembly of claim 2 further comprising: a tension spring means secured to said first mentioned member and to said bell crank means for urging said bell crank means towards said first mentioned member.

4. The tension link assembly of claim 1 further comprising: compression surface means on said housing and cooperative compression surface means on said bell crank adapted to secure said fastening member and supportsaid suspended member at the predetermined tension imparted to the suspended member by said screw cam means.

5. A tension link assembly for supporting a suspended member at a first predetermined tension, the tension link assembly comprising: a housing extending downwardly from a member and pivoted thereupon; a fastening member slidably mounted in said housing having a first fastening means on the lower end thereof adapted to extend beyond the bottom of said housing; control means for sliding said fastening member upwardly in said housing to support said suspended member at said first predetermined tension; the suspended member including: a post extending upwardly toward and adjacent to said first fastening means; a second fastening means fixedly mounted on the top of said post and adapted to separate from said post when a second predetermined relative tension occurs therebetween, the tension link assembly adapted to secure said first fastening means to said second fastening means so as to support said suspended member with said first predetermined tension.

6. The invention of claim 5 further comprising: a projection on said fastening member adjacent said first fastening means adapted to abut said post.

7. The invention of claim 6 further comprising: a tension spring means secured to the said member pivotally mounting said housing, and to said control means, the tension spring means adapted to pivot said control means away from said post.

8. The invention of claim 5 further comprising: means on said housing cooperating with compression surface means included in said control means for securing and supporting said suspended member with said first predetermined tension imparted thereto by said control means which is less than that necessary to separate said second fasteningmeans and said post.

9. The invention of claim 5 wherein the control means includes a compression spring means on said fastening member adapted to bias said fastening member in an upward direction relative to said suspended member.

10.'A tension link assembly comprising: a stationary member; a first pivot pin on said stationary member; a housing extending downwardly from said stationary member and pivoted on said pin; a fastening member in said housing having a hooked end on the lower end thereof extending beyond said housing and adapted to be operatively fastened to a complementary fastened member; a first Washer fixed to the upper end of the fastening mem: her; a second Washer slidably mounted on said fastening member on the mid-portion thereof; a first spring surrounding said fastening member mounted between said first and second washers so as to bias the second washer downwardly relative to said first washer; a shoulder portion on said fastening member below said second washer; means defining a hole in said fastening member below said shoulder portion transversely of the longitudinal axis thereof; first thread means formed on one side of said housing transverse to the longitudinal axis thereof and ali ned with the hole defined in said fastening member; a setscrew extending through said housing, the hole defined in said fastening member, and having a second thread means on one end thereof cooperating with said first thread means for seelctive longitudinal movement of the setscrew; first cam means formed on the other end of said setscrew; a second pivot pin mounted on the housing adjacent said first cam means; a bell crank pivotally mounted on said second pivot pin; a second cam means on said bell crank cooperating with said first cam means to pivot said bell crank upon selective rotation of said setscrew; third cam means formed on and extending from said bell crank beneath the second washer adapted to lift said second Washer so as to impart a predetermined tension to said fastening member and said complementary fastened member; second spring means secured to said stationary member and said bell crank adapted to pivot said bell crank and housing away from said complementary fastened member.

References Cited in the file of this patent UNITED STATES PATENTS 556,547 Marichal Mar. 17, 1896 1,208,298 Cunny Dec. 12, 1916 1,298,072 McNabney et al Mar. 25, 1919 1,394,962 Bate 'Oct. 25, 1921 1,524,175 Eggers Jan. 27, 1925 1,592,067 Beetem July 13, 1926 1,681,050 Robinson Aug. 14, 1928 1,822,236 Pilblad Sept. 8, 1931 1,931,850 Moore Oct. 24, 1933 1,936,461 Sando et a1. Nov. 21, 1933 2,605,123 Gland-Mantle July 29, 1952 2,647,287 Jones Aug. 4, 1953 2,651,482 OConnor Sept. 8, 1953 2,709,611 Claud-Mantle May 31, 1955 2,833,005 Barry May 6, 1958 2,844,048 Bennett et a1. July 22, 1958 2,951,421 Katzen Sept. 6, 1960 

1. A TENSION LINK ASSEMBLY COMPRISING: PIVOT MEANS ON A MEMBER PIVOTALLY MOUNTING A HOUSING; A FASTENING MEMBER SLIDABLY MOUNTED IN SAID HOUSING AND HAVING A HOOK MEANS ON THE LOWER END THEREOF ADAPTED TO TENSIONALLY SUPPORT A SUSPENDED MEMBER; COMPRESSION MEANS FOR URGING SAID FASTENING MEMBER IN AN UPWARD DIRECTION; BELL CRANK MEANS MOUNTED ON SAID HOUSING FOR URGING SAID COMPRESSION MEANS INTO A COMPRESSED CONDITION; MEANS MOUNTING SAID BELL CRANK FOR LIMITED MOTION TO LIMIT THE COMPRESSIVE FORCE EXERTED BY THE BELL CRANK UPON SAID COMPRESSION MEANS TO A PREDETERMINED AMOUNT; MEANS MOUNTED TO THE HOUSING AND ENGAGED WITH THE BELL CRANK FOR IMPARTING SAID LIMITED MOTION TO SAID BELL CRANK MEANS SO AS TO IMPART A PREDETERMINED SUPPORT TENSION TO THE SUSPENDED MEMBER. 